Extrusion of resins

ABSTRACT

A SHEET OF FOAMED THERMOPLASTIC SYNTHETIC RESIN IS MADE BY EXTRUDING A FOAMABLE THERMOPLASTIC SYNTHETIC RESIN THROUGH A SLIT DIE. THE DIE COMPRISES AN EXIT ZONE DEFINED BY A PAIR OF OPPOSING SURFACES. ONE OF THE SURFACES MOVES IN THE DIRECTION OF THE EXTRUSION AND IS CONVEX IN THAT DIRECTION. THE OTHER SURFACE IS PLANAR. FOAMING OF THE RESIN OCCURS AS IT MOVES THROUGH THE EXIT ZONE. THE RELATIVE SPACING OF THE SURFACES IS SUCH THAT THEY CONTACT THE EXPANDING AND FOAMING RESIN AND A FOAMED RESIN SHEET IS PRODUCED.

DEFENSIVE PUBMCATIUN UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16, 1969, 869 0.G. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed. The files of these applications are available to the public for inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent Office makes no assertion as to the novelty ot the disclosed subject matter.

PUBLISHED JULY 10, 1973 T912,003 EXTRUSION 0F RESHNS Keith Merchant, Newport, and Durgacharan Sen,

Cwmbran, Wales, assignors to Monsanto Chemicals Limited, London, England Filed May 23, 1972, Ser. No. 256,060 Int. Cl. 329d 27/00 US. Cl. 264-51 1 Sheet Drawing. 25 Pages Specification A sheet of foamed thermoplastic synthetic resin is made by extruding a foamablc thermoplastic synthetic resin through a slit die. The die comprises an exit zone defined by a pair of opposing surfaces. One of the surfaces moves in the direction of the extrusion and is convex in that direction. The other surface is planar. Foaming of the resin occurs as it moves through the exit zone. The relative spacing of the surfaces is such that they contact the expanding and foaming resin and a foamed resin sheet is produced.

July 10, 1973 MARCHANT ET AL T9l2,003

EXTRUS ION OF RES INS Filed May 23, 1972 FIG].

FIGZ. F1613. 

